The cushioning dunnage product obtained at the outlet of a cushioning dunnage producing machine comprises generally a resilient band with a central zone of a thickness less than the lateral edges, which have the shape of longitudinal pads or pillows. In order to use such a material in a cushioning fashion to protect various articles during shipment, sections of various lengths are required depending on the volume of the container and the dimensions of the article to be shipped therein. This is why severing devices are needed at the machine outlet.
Up to now, such devices comprised movable knives, as is described for example in U.S. Pat. Nos. 4,699,609 and 5,123,889. In the first of those patents, the cutting device is of the shearing type comprising a fixed blade and a movable blade actuated by an electric motor. The second patent is presented as an improvement to said cutting device, inasmuch as the driving means includes a combination of motor means and an usual mechanical crank-linking rod linkage to provide a better control of the successive cutting operations, by a transformation of the rotative motor means into a linear alternative displacement.
In the above mentioned patents the severing devices of the prior art are operating by a lateral shearing which therefore applies a lateral action upon the plies of the material which have been previously connected together by mechanical means imparting to said plies a rather irregular cohesion, for example by coining, corrugating or the same. The shearing efforts have for consequence to reduce the effects of this friction connection obtained upon the successive plies obtained by the above processes and can even reduce the cohesion of the product at the severed ends.
In opposition to that the severing device of the invention provides a better connection of the plies at each severed end, which has for effect to substantially improve the cohesion of the cushioning dunnage products obtained.